[PATCH net] selftests/bpf: set gopt opt_class to 0 if get tunnel opt failed

When fixing the bpf test_tunnel.sh genve failure. I only fixed
the IPv4 part but forgot the IPv6 issue. Similar with the IPv4
fixes 557c223b643a ("selftests/bpf: No need to drop the packet when
there is no geneve opt"), when there is no tunnel option and
bpf_skb_get_tunnel_opt() returns error, there is no need to drop the
packets and break all geneve rx traffic. Just set opt_class to 0 and
keep returning TC_ACT_OK at the end.

Fixes: 933a741e3b82 ("selftests/bpf: bpf tunnel test.")
Signed-off-by: Hangbin Liu <redacted>
---
 tools/testing/selftests/bpf/progs/test_tunnel_kern.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/tools/testing/selftests/bpf/progs/test_tunnel_kern.c b/tools/testing/selftests/bpf/progs/test_tunnel_kern.c
index 9afe947cfae9..ba6eadfec565 100644
--- a/tools/testing/selftests/bpf/progs/test_tunnel_kern.c
+++ b/tools/testing/selftests/bpf/progs/test_tunnel_kern.c

@@ -508,10 +508,8 @@ int _ip6geneve_get_tunnel(struct __sk_buff *skb)
 	}
 
 	ret = bpf_skb_get_tunnel_opt(skb, &gopt, sizeof(gopt));
-	if (ret < 0) {
-		ERROR(ret);
-		return TC_ACT_SHOT;
-	}
+	if (ret < 0)
+		gopt.opt_class = 0;
 
 	bpf_trace_printk(fmt, sizeof(fmt),
 			key.tunnel_id, key.remote_ipv4, gopt.opt_class);

-- 
2.26.2